Method of manufacturing a golf club face

ABSTRACT

Embodiments of methods of manufacturing a face plate for a golf cub are generally described herein. In one exemplary embodiment, a method for manufacturing a golf club face plate comprises: providing a face plate material, and milling the face plate material in an elliptical pattern to form a central region comprising, a first elliptical outer edge and a transition region extending from the first elliptical outer edge to a second elliptical outer edge. In this exemplary embodiment, each point along the second elliptical outer edge is displaced outward from the first elliptical outer edge by a predetermined distance. Other embodiments herein may be described and claimed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to, incorporates by reference, and is adivisional application of prior application Ser. No. 10/803,837 filedMar. 17, 2004 originally titled, Method of Manufacturing a Golf ClubFace.

BACKGROUND OF THE INVENTION

This invention relates generally to golf clubs and, in particular, toso-called metal wood drivers.

Recent developments in golf club design have included improvements indrivers, which are clubs used primarily to strike a golf ball resting ona golf tee. These improvements have resulted in drivers with club headsconsisting of a hollow shell usually made of metal, such as steel,aluminum, or titanium. These hollow shells have relatively thin wallsincluding a thin front wall that is used to impact the golf ball. Inorder to prevent the front wall of these hollow shells from permanentlydeforming or cracking upon ball impact, it has become necessary toreinforce the front wall. One example of a golf club head consisting ofa hollow metal shell with a reinforced front wall is disclosed in U.S.Pat. No. 4,511,145 to Schmidt. The club head disclosed in the Schmidtpatent has an arched ridge extending between the heel and toe ends ofthe front wall. The arched ridge design of the Schmidt provides adequatereinforcement for drivers of moderate head volume, however, in an effortto obtain better and better performance from these hollow metal wooddrivers, golf club manufacturers have increased the head volume from themoderate volume of 200 cc's to over 400 cc's during the past decade. Ashead size increases, less and less material is available to reinforcethe front wall of the club face within acceptable weight limitations(i.e., around 200 grams mass). Consequently, more exotic materials suchas forged or cold rolled titanium faces welded to a cast titanium bodyhave been utilized in these super-oversized drivers. The rear surfacesof the front walls of these super-oversized drivers must be carefullycontoured to provide adequate structural strength with a minimum amountof material.

The most critical region to reinforce, is, of course, the ideal ballimpact point of the front wall. Because most golfer's swings varysomewhat from impact to impact, the reinforced region of the front wallmust be distributed around the ideal impact point. However, sincevariations in a golfer's swing tend to be more in the heel and toedirection, rather than up or down, the distribution of hits tends to bewithin a horizontal, elliptical region rather than a circular regioncentered around the center of the club face. Accordingly, an elliptical,rather than a purely circular reinforcement is preferable. One exampleof a golf club head having a face with a contoured rear surface is U.S.Pat. No. 6,354,962 to Galloway, et al. The club head disclosed inGalloway has a face plate reinforced with elliptical regions that areformed as part of the forging process of the face plate. For clubs inwhich the club face is machined from a wrought alloy sheet or othersheet material, forming an elliptical reinforced region presents specialproblems. The face cannot be machined properly on a lathe because thelathe will produce only a circular reinforced region. One manufactureris known to use an end mill that makes multiple elliptical passes tomachine the reinforced region of the golf club face. This operation is,however, time consuming and unnecessarily costly.

SUMMARY OF THE INVENTION

According to the present invention, a golf club head is manufactured byremoving a portion of the rear surface of a face plate to form a centralthickened region surrounded by a transition region that tapers to athinner peripheral region. According to the illustrative embodiment, theface plate is a rolled sheet titanium alloy between 0.130 and 0.180inches thick, a portion of the transition region of which is machinedaway to leave the central thickened region and to form the transitionregion and the thinner peripheral region. Rather than forming the rearsurface contour of the face plate by making multiple passes with an endmill, however, the central portion, the transition region and theperipheral region are formed in a single elliptical pass with a specialcutting tool. The cutting tool, or “form cutter” has a conical lateralcutting surface, which forms the transition region and the peripheralregion in a single operation. Use of this form cutter to machine thetransition region and peripheral region in a single operation yieldsgreater uniformity in the rear surface contour of the face plate andsaves substantial time and money over prior art multiple pass machiningoperations.

BRIEF DESCRIPTION OF THE DRAWING

The present invention will be better understood from a reading of thefollowing detailed description, taken in conjunction with theaccompanying drawing figures in which like references designate likeelements, and in which:

FIG. 1 is a partially cut-away rear perspective view of a golf clubincorporating features of the present invention;

FIG. 2 is a rear cross-sectional view of the golf club of FIG. 1;

FIG. 3 is a cross-sectional view of the golf club of FIG. 2 taken alongline 3-3;

FIG. 4 is a cross-sectional view of the golf club of FIG. 2 taken alongline 4-4;

FIG. 5 is a side view of a machining step in the method of forming golfclub head in FIG. 2;

FIG. 6 is a side view of an alternative cutting tool used in themachining step of FIG. 5; and

FIG. 7 is a side view of another alternative cutting tool used in themachining step of FIG. 5.

DETAILED DESCRIPTION

The drawing figures are intended to illustrate the general manner ofconstruction and are not necessarily to scale. In the description andthe in the drawing figures, specific illustrative examples are shown andherein described in detail. It should be understood, however, that thedrawing figures and detailed description are not intended to limit theinvention to the particular form disclosed but are merely illustrativeand intended to teach one of ordinary skill how to make and/or use theinvention claimed herein and for setting forth the best mode forcarrying out the invention.

Referring to FIG. 1, a golf club 10 includes a head 12, a hosel 14 and ashaft 16. Head 12 includes a hollow body 18 made of a metal materialsuch as titanium. Hollow body 18 is formed as a shell 20, which may beassembled from a series of forged pieces but, in the illustrativeembodiment, comprises a titanium investment casting. A face plate 22 isattached by conventional means such as plasma or electron beam weldingto a corresponding opening 23 in shell 20 to form hollow body 18. Faceplate 22 may be a conventional forged blank but, in the illustrativeembodiment, comprises a rolled sheet titanium blank that is machinedprior to welding to shell 20 as described more fully hereinafter.

As noted hereinbefore, because a golfer's swing tends to vary more inthe heel-toe direction than it does up or down, the inventor of thepresent invention determined that the most efficient reinforcement wouldbe an elliptical thickened region oriented so that the major axis of thereinforced region was substantially horizontal when the club is held inits normal position for addressing the ball. Accordingly, face plate 22includes a central thickened region 24 that is substantially ellipticalin shape with its major axis 26 oriented horizontal when the club isheld in its normal address position. In the illustrative embodiment,central thickened region 24 is between 0.130 and 0.180 inches inthickness. Central thickened region 24 is surrounded by a transitionregion 28 that tapers from the central thickened region 24 to aperipheral region 30, which in the illustrative embodiment is 0.080 to0.120 inches thick. Transition region 28 is also elliptical, however,for reasons that are explained more fully hereinafter, the major axisand minor axis of transition region 28 are a fixed amount larger thanthe respective major and minor axis of central thickened region 24.Accordingly, the aspect ratio of transition region 28 is lower than theaspect ratio of central thickened region 24 (in other words, transitionregion 28 is a “fatter” ellipse than central thickened region 24).

With reference to FIGS. 2-5, prior to assembly of face plate 22 to shell20, the rear contours of face plate 20 are formed by a machiningoperation shown schematically in FIG. 5. The process begins with a blankface plate 32, which in the illustrative embodiment comprises a blankstamped from a rolled sheet of titanium alloy. The blank face plate 32has a thickness equal to the final thickness of the central thickenedregion 24 of the finished face plate 22, which as noted hereinbefore isfrom 0.130 to 0.180 inches in thickness. The rear surface of blank faceplate 32 is machined by using a cutting tool 34 to remove a portionthereof. The tip of cutting tool 34 has a lateral cutting surface 36 anda lower cutting surface 38. Lower cutting surface 38 is perpendicular tothe axis 40 of cutting tool 34. Lateral cutting surface 36 is angledupward with respect to lower cutting surface 38 by an angle 42 of fromabout 5 to 20 degrees, but preferably about 13 degrees such that lateralcutting surface 36 defines a generally inverted conical frustum surfaceof revolution 44 as cutting tool 34 is rotated about its axis 40.Lateral cutting surface 36 may have straight edges as shown in FIG. 5,or may have edges 36 b that are concave downward as in the cutting tool34 b shown in FIG. 6, or may have edges 36 c that are convex downward asin the cutting tool 34 c shown in FIG. 7. yielding a conical frustumsurface of revolution (and corresponding transition regions) havingcorrespondingly curved sides.

As can be seen from FIG. 5, as the lower cutting surface 38 and lateralcutting surface 36 are brought into contact with rear surface 46 ofblank face plate 32, lower cutting surface 38 and lateral cuttingsurface 36 cooperate to cut a tapered transition region 28 and a flatperimeter region 30 simultaneously in a single pass, thus obviating theneed to make multiple passes with an end mill as in the prior art. Withparticular reference to FIGS. 2-4, the major axis 26 of centralthickened region 24 is from 0.65 to 1.05 inches in length. The minoraxis 48 of central thickened region 24 is 0.25 to 0.45 inches in length.Accordingly, the aspect ratio of central thickened region 24 is between1.4 and 4.2. In the illustrative embodiment, major axis 26 isapproximately 0.85 inches and minor axis 48 is approximately 0.35 inchesyielding an aspect ratio of approximately 2.4.

Major axis 50 and minor axis 52 of transition region 28 are a fixedamount “6” greater than the respective major and minor axes of centralthickened region 24, wherein the 6 value can be chosen from a range ofabout 0.40 inches to about 1.20 inches. In the illustrative example, themajor axis 50 and minor axis 52 are approximately 0.86 inches greaterthan the respective major and minor axes of central thickened region 24.Thus, major axis 50 in the illustrative embodiment is approximately 1.71inches in length and minor axis 52 of transition region 28 isapproximately 1.21 inches in length. Thus, the aspect ratio oftransition region 28 is approximately 1.4 as opposed to the 2.4 aspectratio of central thickened region 24. The high aspect ratio centralraised portion surrounded by the lower aspect ratio transition regionprovides optimum distribution of material for improved performance andreliability.

Although certain illustrative embodiments and methods have beendisclosed herein, it will be apparent from the foregoing disclosure tothose skilled in the art that variations and modifications of suchembodiments and methods may be made without departing from the spiritand scope of the invention. Accordingly, it is intended that theinvention should be limited only to extent required by the appendedclaims and the rules and principals of applicable law.

1. A method for manufacturing a golf club face plate comprising:providing a face plate material; milling the face plate material in anelliptical pattern to form: a central region comprising a firstelliptical outer edge; and a transition region extending from the firstelliptical outer edge to a second elliptical outer edge; wherein: eachpoint along the second elliptical outer edge is displaced outward fromthe first elliptical outer edge by a predetermined distance.
 2. Themethod of claim 1, wherein the central region comprises a thicknesssubstantially similar to a thickness of the face plate material.
 3. Themethod of claim 1, wherein the central region comprises a thickness ofabout 0.13 inches to about 0.18 inches.
 4. The method of claim 1,wherein the predetermined distance is about 0.40 inches to about 1.20inches.
 5. The method of claim 1, wherein milling the face platematerial comprises using an end mill to mill the face plate material. 6.The method of claim 1, wherein the central region comprises a major axisof about 0.65 inches to about 1.05 inches.
 7. The method of claim 1,wherein the central region comprises a minor axis of about 0.25 inchesto about 0.45 inches.
 8. The method of claim 1, wherein an aspect ratioof the central region is about 1.4 to about 4.2.
 9. The method of claim1, wherein an aspect ratio of the second elliptical outer edge is lessthan an aspect ratio of the central region.
 10. The method of claim 1,wherein milling the face plate material comprises using a cutting toolcomprising a first cutting surface and a second cutting surfacedifferent from the first cutting surface.
 11. The method of claim 10,wherein the second cutting surface comprises a perpendicularconfiguration to a rotating axis of the cutting tool.
 12. The method ofclaim 10, wherein the first cutting surface creates an angle withrespect to the second cutting surface of about 5 degrees to about 20degrees.
 13. The method of claim 1, wherein the transition regioncomprises a non-linear transition between the first elliptical outeredge and the second elliptical outer edge.
 14. The method of claim 1,wherein the transition region comprises a non-linear transition having aconvex configuration.
 15. The method of claim 1, wherein the transitionregion comprises a non-linear transition having a concave configuration.16. The method of claim 1, wherein the transition region comprises afrustrum-like region.
 17. The method of claim 1, wherein milling theface plate material further comprises milling the face place material ina single elliptical orbit.
 18. A method for manufacturing a golf clubhead: providing a golf club head shell comprising an opening to receivea faceplate; providing a faceplate; and coupling the faceplate to theopening; wherein, providing a faceplate further comprises: milling aface plate material in an elliptical pattern to form: a central regioncomprising a first elliptical outer edge; and a transition regiontapering from the first elliptical outer edge to a second ellipticalouter edge; wherein: cross-section profiles of the transition regionfrom the first elliptical outer edge to the second elliptical outer edgeare substantially similar when the cross sectional profiles are takenalong perpendicular directions that are collinear with a major axis anda minor axis of the second elliptical outer edge.
 19. The method ofclaim 18, wherein: the central region comprises a major axis of about0.65 inches to about 1.05 inches; the central region comprises a minoraxis of about 0.25 inches to about 0.45 inches; an aspect ratio of thecentral region is about 1.4 to about 4.2; and a thickness of the centralregion is about 0.13 inches to about 0.18 inches.
 20. The method ofclaim 18, wherein the transition region comprises a convexconfiguration.
 21. The method of claim 18, wherein the transition regioncomprises a concave configuration.
 22. A method for manufacturing a golfclub: providing a golf club head comprising a faceplate; and couplingthe golf club head to a shaft; wherein, the faceplate comprises: a firstregion comprising a first elliptical outer edge comprising a firstaspect ratio, a first major axis, and a first minor axis; and a secondregion extending from the first elliptical outer edge to a secondelliptical outer edge, comprising a second aspect ratio, a second majoraxis, and a second minor axis, the second major axis being equal to thefirst major axis plus a predetermined distance, and the second minoraxis being equal to the first minor axis plus the predetermineddistance.
 23. The method of claim 22, wherein: the first and secondmajor axes are collinear with each other; and the first and second minoraxes are collinear with each other.
 24. The method of claim 22, wherein:the first major axis is about 0.65 inches to about 1.05 inches; thefirst minor axes is about 0.25 inches to about 0.45 inches; and theaspect ratio of the first region is about 1.4 to about 4.2.
 25. Themethod of claim 22, wherein the second region comprises a non-lineartransition from the first elliptical outer edge to the second ellipticalouter edge.